Genetic predisposition and resistance to early coronary heart disease (CHD) will be studied in a large sample of population-based pedigrees in Utah (100 with premature CHD, 40 with longevity, and 40 control pedigrees). CHD incidence and risk factor data will be sought for living members of 180 descending pedigrees, estimated to contain approximately 9000 persons. An estimated 2800 hospital charts will also be abstracted for deaths and persons with nonfatal CHD. Five thousand persons including children in 100 of these pedigrees will be screened twice in five years. Data collection will include blood cholesterol, triglycerides, HDL, and glucose, height, weight, skinfolds, and blood pressure; socioeconomic status, smoking, illnesses, medications, and hospitalizations; physician's history and physical exam, detailed family history and dietary evaluation. For adults age 18 plus, leisure and occupational activity questionnaires, ECGs, bench test estimates of functional aerobic capacity, and psychological tests (including Type A-B personality) will be collected. Analyses will (1) determine the proportion of all premature coronary disease in a general population found in high risk pedigrees (and longevity in low risk pedigrees); (2) classify prone and resistant pedigrees by syndromes involving CHD risk factors, and determine the frequency of pedigrees by types; (3) assess gene-environment interaction, and (4) identify genetic mechanisms using pedigree diagramming, descriptive genetic indices, and maximum likelihood model testing. Results will elucidate underlying mechanisms of disease causation and provide important information for use in programs of CHD detection treatment and prevention.